An axolotl salamander shows off its extra left arm, which was grown with the help of a UC Irvine research team studying regeneration. UC IRVINE

The Team

•Susan Bryant, acclaimed

biologist

•Catherine (Kate) McCusker, postdoctoral researcher

•Dr. Jason Lee, postdoctoral

researcher

•Anne Phan, graduate student

•Jeff Lehrberg, graduate student

•Cristian Aguilar, graduate student

•Veronica Aguilar, lab manager

Vocabulary

Blastema (blass-teem-uh): an area that forms at the end of an amputation site on a salamander or on the wound site of a salamander that attracts special cells that can grow a limb.

Axolotl (axe-ih-lot-ul): the type of salamanders the lab uses. They originally come from Mexico.

Epithelium (ep-ih-theel-ee-um): is the top layer of skin on an animal.

Graduate student researcher Anne Phan was in the lab one recent Thursday, readying salamanders to get their photo taken.

She's documenting the growth of an extra arm that has sprouted on one side of their bodies thanks to a UCI research team.

The team studies regeneration on salamanders in the hopes that one day, people will be able to grow limbs like salamanders do.

The lab invented a way to grow extra limbs on salamanders without doing an amputation, which has advanced the study of regeneration, the team says. It is the lab's calling card.

David Gardiner heads the research.

He is professor of developmental and cell biology at the School of Biological Sciences, and he has been working on regeneration since 1982.

There are no eureka moments in regeneration research, Gardiner said. It's slow and tedious. But there are "eurekette" moments, he said. "We get excited about it."

Gardiner's team of about 15 people work in the Natural Sciences II building, where they study regeneration in a variety of ways. The team includes seven undergraduate student researchers, who work with graduate students, and six undergraduate students, who take care of the salamanders.

The lab breeds its own salamanders too, for efficiency. Until the salamanders are called up for duty, they reside in plastic containers, just like the ones that store food in your refrigerator.

Phan is a fan of salamanders. "They are some of the coolest animals," she said. "Our favorite ones we keep as pets." The "pets" get to stick around as breeders.

•Humans can regenerate a lost fingertip if it is lost above the first knuckle.

•Emma Stone and Rhys Ifans, stars of "The Amazing Spider-Man," visited Gardiner's lab, which was the model design used for the movie.

•The lab breeds its own salamanders, which from egg to use is about three months. In the lab, they can live for five or more years.

The Department of Defense funds the UCI lab. "If you look at the history of medicine, most of it comes out of military conflicts," Gardiner said. The military needs to replace skin and limbs.

Different responses to limb loss:

Humans make scars (collagen); salamanders make a blastema, which grows a new limb.

How the lab grows extra limbs on a salamander:

1) Make a wound in the top layer of skin on the arm. 2) Dissect a nerve, sever it and bring it to the middle of the wound site, where it interacts with the wound. 3) Grab skin from the other side of the arm to cover the area. Now the skin attracts blastema, special cells that prompt regeneration.

Gardiner's hypothesis:

Salamanders aren't special. The default is regeneration, but regeneration in humans becomes restricted. Animals that don't regenerate suppress the process. "That's what I would argue."

Why would it be restricted in humans?

There's a relationship between regeneration and immune systems, Gardiner said. The immune response is important in humans to fight infection.

Why no immune system interference here?

Salamanders live in a world where they're constantly exposed to pathogens. Through evolution, they've developed the ability to heal wounds fast.

How might humans grow limbs in the future?

It's a matter of cells talking to cells, but they do this outside of the cells, so it could be an applied ointment or a "smart bandage," Gardiner said.

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